I said, "Learn to spell, you fucking noob." This statement has nothing to do with proper grammar.

I separated it into two clauses because the first one can stand by itself, but the second one becomes a subordinate clause if you don't add to it. "Which has nothing to do with proper grammar," can not stand by itself because it has no subject and the first "Which" becomes an intransitive pronoun meaning it has no subject attached to it. By adding, "This statement has nothing to do with proper grammar," effectively turns your subordinate clause into an independent clause (full-blown sentence).